Bir de böyle deneyin:
    <body id="register_bg">
        <div id="register">
            <div class="sign-in-wrapper">
                <aside>
                    <figure>
                        <a href="index.html"><img src="img/logo_sticky.svg" width="140" height="35" alt=""></a>
                    </figure>
                    <div class="access_social">
                        <a href="#0" class="social_bt facebook">Login with Facebook</a>
                        <a href="#0" class="social_bt google">Login with Google</a>
                    </div>
                    <div class="divider"><span>Or</span></div>

                    <?=@$cevap?>
                    <form method="post">

                        <div class="form-group">
                            <input class="form-control" type="text" name="kadi"  placeholder="Kullanıcı Adınız">
                            <i class="icon_mail_alt"></i>
                        </div>
                        <div class="form-group">
                            <input  class="form-control" type="password" name="pass" id="password" placeholder="Şifreniz">
                            <i class="icon_lock_alt"></i>
                        </div>
                        <div class="clearfix add_bottom_15">
                            <div class="checkboxes float-left">
                                <label class="container_check">Beni hatırla
                                  <input type="checkbox">
                                  <span class="checkmark"></span>
                              </label>
                          </div>
                          <div class="float-right"><a id="forgot" href="#0">Forgot Password?</a></div>
                      </div>
                      <input type="submit"  value="Giriş Yap" class="btn_1 full-width mb_5">

                      <div class="text-center mt-2"><small>Don't have an acccount? <strong><a href="register.html">Sign Up</a></strong></small></div>
                  </form>

                  <div class="copy">© 2020 FooYes</div>
              </aside>
          </div>
      </div>

      <!-- /login -->

      <!-- COMMON SCRIPTS -->
      <script src="js/common_scripts.min.js"></script>
      <script src="js/common_func.js"></script>
      <script src="assets/validate.js"></script>

  </body>
</html>